A variety of compounds have been investigated for their antiviral properties. For example, the dyes Trypan blue, Evans blue, Congo Red and derivatives thereof, as well as additional related compounds, have been examined as potential antiviral agents (Alarcon et al., Antiviral Research, 4, 231-243 (1984); Thorne et al., J. Gen. Viral., 64, 1365-1368 (1983); Westin et al., J. of Med. Chem., 14(7), 596-60 (1971); Mohan et al., J. Med. Chem., 34, 212-217 (1991)). Several compounds which have been demonstrated to inhibit replication of the human immunodeficiency virus (HIV) include soluble CD4 protein and synthetic derivatives (Smith, D. H. et al., Science, 238, 1704-1707 (1987); Lifson et al., Science, 241, 712-716 (1988)), dextran sulfate (Ito et al., Antivir Res., 7, 361-367 (1987)), and the dyes Direct Yellow 50 (Balzarini et al., Int. J. Cancer, 37, 451-457 (1986b)), aurintricarboxylic acid (ATA) and Evans Blue (EB) (Balzarini et al., Biochem. Biophys. Res. Commun., 136, 64-71 (1986a)). Some of these antiviral agents have been shown to act by blocking binding of gp120, the coat protein of HIV, to its target, the CD4 glycoprotein of T4 lymphocytes (Smith, D. H. et al. Science, 238, 1704-1707 (1987); Lifson et al., Science, 241, 712-716 (1988); Weaver et al., AIDS Res. Human Retrovir., 6, 1125-1130 (1990)). However, many of these pharmaceutical compounds, in particular the dyes Trypan blue and Congo Red, also mediate additional undesired effects at the cellular and organismic levels, such as induction of congenital abnormalities (Thorne et al., supra) or in vivo metabolism to carcinogens (Mohan et al., supra).
Other dyes hold more promise as pharmaceutical agents and, particularly, as antiviral agents. Recently, several azo dye derivatives, including Direct Red 79, Acid Blue 116, and Acid Red 115, were examined for their efficacy against HIV (U.S. patent application Ser. No. 07/684,258). Despite similarity in the general structure of the twenty-five azo dyes, only two-thirds of the disclosed azo dyes tested were found to be effective at impairing the binding of a CD4 monoclonal antibody (.alpha.CD4) to T4 lymphocytes. These results were similar to those obtained in earlier examinations of dye derivatives, which suggested that possession of certain structural features such as sulfonic acid groups (Akerfeldt et al., J. Medicin. Chem., 14(7), 596-600, 1971) or a biphenyl spacer separating napthalenedisulfonic acid groups (Mohan et al., supra) might be important for binding to CD4, but failed to clearly define features critical for CD4 binding. It is evident that the present state-of-the-art does not allow a prediction of CD4 binding ability to be made for a compound merely as a result of it being an azo dye, or based upon possession of a particular chemical structure.
Additionally, the azo dyes described above which proved effective in inhibiting binding to CD4 all shared the disadvantage of demonstrating significant binding to serum proteins. Such binding limits the use of these dyes as antiviral agents, as it reduces ability to inhibit binding to CD4. Consequently, there remains a need for pharmaceutical agents that are capable of binding the CD4 glycoprotein of T4 lymphocytes, and that demonstrate reduced binding to serum proteins. It is an object of the present invention to provide pharmaceutical compositions containing azo dye derivatives which satisfy these criteria, and therefore demonstrate significant utility for the diagnosis, treatment, and prevention of viral diseases.
It is an additional object of the present invention to provide a method of inhibiting the binding of a virus to CD4-positive T4 lymphocytes, particularly with respect to a retrovirus, and more particularly as regards HIV. It is a further object of the present invention to provide a method of treating and protecting against viral infection, particularly with respect to a retrovirus, and more particularly as regards HIV. It is yet another object of the present invention to provide a diagnostic method of detecting CD4-positive T4 lymphocytes.
These and other objects and advantages of the present invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.